PURPOSE: To provide a safe, practical and extremely advantageous process for the production of a perfluoroalkyl iodide in high efficiency.

CONSTITUTION: A perfluoroalkyl iodide expressed by RfI is produced by reacting a perfluorocarboxylic acid expressed by the formula Rf-COOH with iodine and benzoyl peroxide in an organic solvent. The reaction is carried out by contacting benzoyl peroxide containing water with an organic solvent effective as a solvent of the reaction and essentially incompatible with water, extracting benzoyl peroxide with the organic solvent in the form of a homogeneous or suspending solution, removing the water phase by phase-separation to prepare a homogeneous or suspending solution of the essentially dehydrated benzoyl peroxide in the organic solvent and using the benzoyl peroxide solution as the raw material and solvent of the above reaction.